As a functional polymer membrane, an ion exchange membrane, a reverse osmosis membrane, a forward osmosis membrane, a gas separation membrane and the like are known as membranes having various kinds of functions.
For example, the ion exchange membrane is used in electrodeionization (EDI), continuous electrodeionization (CEDI), electrodialysis (ED), electrodialysis reversal (EDR) and the like.
The electrodeionization (EDI) is a water treatment process wherein ions are removed from aqueous liquids using an ion exchange membrane and an electrical potential to effect ion transport. It differs from other water purification technologies, such as conventional ion exchange, in that it is does not require the use of chemicals such as acids or caustic soda. EDI can be used to produce ultra pure water. The electrodialysis (ED) and the electrodialysis reversal (EDR) are electrochemical separation processes that remove ions and the like from water and other fluids.
In the ion exchange membrane, study on improvement in ionic transport number and pH tolerance has been conducted (for example, see Patent Literature 1 to 3). However, further improvement in performance as the functional polymer membrane has been required, and improvement in characteristics of the functional polymer membrane other than the above has also been demanded.